Currently, China became the world's largest commodity production and suppliers. Development determines the expansion of production scale. However, with the expansion of production scale, air pollution is worsening. The conflict between development and pollution forces our country to find a path in which development, emission reduction and pollution treatments are coordinated and balanced. Only playing tremendous power of science and technology can make the development of our country on the path of health, green and sustainable development.
The concept of indoor air quality (IAQ) was proposed in the developed countries at the late 1970s. At that time, consideration for energy conservation, the sealing performance of housing was greatly improved. The resulting lack of indoor air resulted in the frequent occurrence of indoor pollution. U.S. scientists in the late 1980s, found in a survey that concentrations of harmful pollutants indoor are greater than that of outdoor, some greater than 100 times. Our country related department in 1984 also found in a survey that air pollution indoor in city is more serious than outdoor air, some more than outdoor 56 times. Consumers who install air conditioners are used to close doors and windows when the air conditioners work so as to reduce air conditioning loss. This requires the air conditioner manufacturers to provide the consumers with air conditioners of which the purify ability should be continuously improved.
Air purification modules (parts) chosen in the air conditioners have made progress and development in the decades. The development of the air purification modules for the air conditioners experiences roughly the following stage:
The first generation of products: humidity adjusting modules, which use the cooling dehumidification function of domestic air conditioners to adjust the indoor air humidity, but do not have air purification function.
The second generation of products: multilayer mesh modules, which use the functions of filtering, adsorption processing of the impurities of the special multilayer meshes to effectively purify suspended solids and a few harmful material in indoor air, but cannot process peculiar smell, pathogenic bacteria, viruses, microorganisms and most of organic pollutants in indoor air. Further, regular cleaning the multilayer mesh causes secondary pollutions at the same time. The biggest drawback of this technical solution is that when improving the filtering effect, the wind resistance will necessarily be increased; while reducing the wind resistance, the filtering effect will necessarily be reduced.
The third generation of products: compound air purification modules. This module increases static dust removal, electronic dust collection, anion generator, ozone generator and low temperature plasma generator on the basis of the second generation of products. The third generation of products can eliminate smoke and dust and have the functions of disinfection, sterilization, peculiar smell removal, but there still exist ills that the organic pollutants can not be effectively decomposed.
The forth generation of products: air purification modules using molecular complexation technology. This technology includes wet molecular complexation technology with adding water and dry molecular complexation technology without adding water. However, this technology also has fatal flaws: first, the service life of the molecular complex filters is only two years, if changing the molecular complex filters, this may cause the second pollution; second, specific molecular complexes can only react with certain organic matter, but there are three thousands of organic pollutants in the air, we cannot provide a kind of complex filters for each organic pollutant to solve the pollution problem.
The fifth generation of products: air purification modules using cold catalyst and photocatalytic technology. This technology is not mature enough, and is still in the theory research phase. At room temperature and atmospheric pressure, this kind of products can decompose many harmful and peculiar smell gases into smelless and harmless substance. In order to improve air purification rate, most of the manufacturers use the technical solutions of increasing the specific surface area of the cold catalyst and photocatalyst, by loading nano materials on filters of porous materials, so that the filters can be changed from pure physical absorption into absorption and decomposition at the same time. In the standard experimental test, the air purification rate of this kind of air purification modules is high in the first dozens of minutes, but is significantly reduced later; after 180 minutes, the air purification rate is too low to be acceptable. The reason is that when the filters are just opened to use, the adsorption performance of the filters is high; later, adsorption is gradually saturated, the air purification rate cannot be quickly restored to the initial level due to the lack of effective desorption.
The sixth generation of products: hydroxyl water purification modules, which adopts advanced oxidation technology to purify. The advanced oxidation technology is a hot technology in recent years, which uses hydroxyl radicals as the main antioxidant to reach with organic matter. Organic free radicals generated in the reaction can continue to participate in the chain reaction of the hydroxyl radicals, or produce further oxidative decomposition reaction after generating organic peroxide free radicals until being degraded into the final products carbon dioxide and water, thereby achieving the purpose of oxidative decomposition of organic matter. The molecular formula of hydroxyl is HO., and has a strong oxidizing property. An encapsulation equipped with hydroxyl water purification modules contains hydroxyl water of mineral water having 15 mg˜60 mg/L calcium, hydroxylated mineral water can be sprayed on a surface of an evaporator to purify. The advanced oxidation reaction has high reaction speed, even to one over one million of a second.
Although the hydroxyl can cause an advanced oxidation reaction in the aqueous solution to effectively purify the water pollution, it cannot directly purify in liquid phase the three thousands of organic pollutants in gas phase. Thus, this kind of advanced oxidation technology which uses hydroxyl radicals as the main antioxidant is usually used in water purification field or air purification where environment humidity is large.
Nowadays, most of the domestic air conditioner manufacturers use only the second generation air purification technology and the third generation air purification technology. A few foreign air conditioner manufacturers use the fifth generation air purification technology and the sixth generation air purification technology, but because the technical issues are not thoroughly solved, air purification effect is not good.
Further, China is one of the countries that can be definited as the world's 13 most water-poor individuals. The shortage of water resources is one of the most outstanding problems which our country faces in the 21st century. And the water pollution situation in our country is still severe; this increases the shortage of water resources and forms a larger real threat to common people drinking water safety, economic and social sustainable development.
In order to performing advanced treatment to the reclaimed water level 1B and secondary discharged from 93% of the sewage treatment plant to achieve the reclaimed water level 1A standard so that the wastewater can be reused, thus, water can be recycled many times. The common technical solutions in domestic and foreign include: ozone oxidation, high iron oxidation and membrane separation technology.
Ozone oxidation technology: the oxidation-reduction potential of the ozone O3 is 2.07V. The ozone has strong oxidation ability, and can cause the pollutants in water oxidation, decomposition, purification, bleaching, deodorization, removal of peculiar smell, sterilization, algae inhibition, disinfection. The ozone can reduce the biochemical oxygen demand (BOD) and chemical oxygen demand (COD), and eliminate surfactant bubbles. The disadvantages are that oxidative activity of the ozone has a high selectivity and it is difficult to remove the BOD and COD in the water. Meanwhile, excess ozone oxidation process will produce some by-products, of which some even have greater toxicity.
High iron oxidation technology: ferrate as non-chlorine-based efficient multi-function water treatment chemicals has a wide range of applications in water treatment field. Common ferrate includes potassium ferrate and sodium ferrate. In acidic medium, the oxidation-reduction potential of the ferrate is 2.20V, which is greater than 2.07V of the ozone, and also far greater than 1.36V the chlorine. Thus, the ferrate has high performance of oxidation, purification, bleaching, deodorization, sterilization and disinfection and other performance. Further, the ferrate has the unique function of flocculation, and can remove 80% of the suspended solids in the level 2 reclaimed water in the sewage treatment plant. The disadvantages of the high iron oxidation technology are that chemicals are needed to be added into the water, and mass production of ferrate requires a lot of energy, and also can produce a lot of pollution discharged.
Membrane separation technology: the pressure drive membrane separation process commonly used in water treatment includes micro filter, ultrafiltration, nanofiltration, etc. The advanced treatment of the reclaimed water usually adopts micro filter and ultrafiltration. Drinking water treatment adopts nanofiltration. The water quality is not affected by climate and can maintain stable. The disadvantages are that micro filter, ultrafiltration can do little about heavy metal iron pollution; meanwhile, in order to maintain the membrane permeability not to drop significantly, it must be regularly reverse pressure washed with water, causing water utilization rate reduced and waste of valuable water resources.
Today, only some of the domestic sewage treatment plants use the high iron oxidation technology, a few domestic sewage treatment plants use the membrane separation technology, most of foreign sewage treatment plants currently use the ozone oxidation technology and prepare to update for the membrane separation technology. The majority of domestic sewage water treatment plants do not do any advanced treatment to the reclaimed water which is discharged paranormally, resulting in new environmental pollution problems.